Investigation on the optimal GDL thickness design for PEMFCs considering channel/rib geometry matching and operating conditions

Abstract

The thickness of gas diffusion layer (GDL) has a significant impact on the internal mass transfer process inside polymer electrolyte membrane fuel cells, and the GDL-flow channel joint design is critical to improve the fuel cell performance. However, previous research rarely considered the effect of flow channel/rib width or operating conditions on the design of GDL thickness. In this work, a reduced-dimensional simplified model is proposed by multi-chamber discretization method. The two-dimensional diffusion process which is affected by GDL thickness and rib width is investigated. The balance between gas transport distance and water drainage capacity is the key to determining the optimal GDL thickness, and this balance is affected by rib width. As the channel/rib narrowed from 1.0 to 0.2 mm, the optimal GDL thickness decreased by 58.5%, and the maximum current density increased by 29.8%. Based on these analyses, a novel joint design method of GDL thickness and channel/rib width based on balancing the two-dimensional mass transfer is proposed to achieve the enhancement of overall mass transfer capability and the best performance. This research provides a critical insight for the multi-component joint design, which is fundamental in fuel cell development.